Explain why the circulation of substances is considered the main condition for the existence of a natural community.

Main conditions:
1) the ability to reproduce;
2) the ability to withstand adverse environmental conditions;
3) species diversity;
4) the balance of the circulation of substances;
5) availability of food and energy;
The main condition is a constant supply of energy.
The presence of a stable and efficient food chain, since it is it that is the basis of any ecosystem, and therefore of a natural community. External energy is transferred to the body in heat. Energy is lost, and during the transition from body to body only 10% is transferred